Flexible plastic sheets inclusive of thermoplastic film usually have a somewhat slimy gloss and a sticky touch characterizing conventional plastic sheets, which are disliked by users in some applications of such sheets. To alleviate such gloss and to improve the touch of the sheet, several techniques have already been known, for example, a technique by which the sheet surface is embossed to take such gloss off and simultaneously to provide the surface with irregularities, and a technique by which a third ingredient is previously mixed into raw material for the sheet so that desired alleviation of the gloss and improvement on the touch may be achieved on a step of sheet production.
However, these well known techniques have not been able to achieve adequate improvement in a plastic sheet particularly used for as a surface sheet in disposable hygienic wearable articles such as sanitary napkins and disposable diapers, because the gloss and feel of the plastic sheet are decisively disliked by users of such wearable articles. U.S. Pat. No. 4,342,314 discloses a technique to provide a flexible plastic sheet with a fibrous appearance and a capillary structure for improvement of appearance as well as touch. According to the technique disclosed by this patent, an appearance closely resembling woven fabric can be achieved, but its surface could be relatively smooth and therefore apt to have yet a slimy gloss even after the sheet has been treated in accordance with the disclosed technique.
Accordingly, it is a principal object of the present invention to provide a flexible plastic sheet on its surface with a plurality of ribs crossing one another so as to create an appearance like woven fabric and thereby to alleviate said undesirable gloss and to improve touch.